Build a Mobile App with Angular 2 and Ionic 2

2016-08-04 05:45 AM

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Build a Mobile App with Angular 2 and Ionic 2

The Ionic Framework enables the creation of cross platform mobile applications with HTML, CSS and JavaScript(Angular). Ionic 1 was built with Angular 1.*, and with the upcoming release of Angular 2, the second major version of Ionic is also imminent.

Ionic 2 is still in beta, but if you are looking to build cross-platform apps quickly, and you already know Angluar 2 or JavaScript, this guide will get you up to speed.

Why Choose Ionic?

You already know HTML/CSS/JS

You can leverage the skills you already have from developing web applications with HTML, JavaScript and CSS to build cross-platform mobile apps. If you work with Angular 2, this will be a seamless transitions.

Take advantage of Progressive Web Apps

Google has been talking about Progressive Web Apps. These are simply web apps that give an app-like user experience to users, and are built with Web Technologies and Ionic 2 is at the fore front of implementing this. An example progressive web app(not built with ionic) is the google io web app: Visit the app in your chrome browser in your phone, click on menu and tap Add to Home Screen. You’ll then be able to load it as an app from your home screen.

Target all major mobile platforms

If you need to quickly build an app for all major mobile platforms (Android, iOS and Windows Phone), having one codebase may be the fastest way to do it, and Ionic is perfect for such a scenario. Updating the app, or rolling uout updates is just as easy as editing one code base.

Native Functionality is easy to implement

What We’ll be Building

We will build a simple app that consumes the github api. Our app will list github users, offer a search box for searching users, and be able to view the number of followers, repos, and gists the user has.

Below is a short video of the finished app.

Install Ionic 2

Ionic 2 is built on top of Cordova, a framework that enables development for cross patform apps with HTML, CSS and JavaScript. Make sure you have nodejs installed.

Install Cordova

$ npm install -g cordova

For Mac/Linux/Unix users, if you see errors with EACCESS, you can run the command as root user with sudo npm install -g cordova, or just fix your npm persmissions..

This installs ionic 2 and its CLI into your workstation, and now we are good to go.

NOTE Ionic 2 is still in beta, and at the time of this article’s publication. To check the version of ionic CLI you have installed, simply run

$ ionic info

You should see results almost similar to this

You can ignore the warnings for now. Most of them are only necessary when we want to deploy or build to either ios or android.

Finally, we need to have TypeScript and Typings installed in our workstation. TypeScript is a superset of JavaScript, and works really well with Angular 2, you can go through the articles by this author to quickly get up to speed with TypeScript. Typings help TypeScript to identify types for non-typescript code.

$ npm install -g typescript
$ npm install -g typings

Hello Ionic 2

Ionic 2 provides a simple starter template to quickly scaffold a simple app. Our app will be called githubIonic, and so we’ll quickly scaffold it with the ionic cli.

In your terminal:

$ ionic start githubIonic tutorial --v2 --ts

The above command scaffolds an ionic project based on a tutorial template ionic provides. It then downloads the necessary npm packages. We’ll build the application using TypeScript, and that’s why we have a --ts flag.

Go to the githubIonic directory with cd githubIonic. We’ll serve the app first, then go through the folder structure. In your terminal, run:

$ ionic serve

You may be asked to select how you would like to serve the ionic app, select localhost:8100 option. Open http://localhost:8100 in your browser, it should looks something similar to this.

Notice that I have opened my Chrome Dev Tools on the side so that the left part where my app is simulates a mobile screen.

We’ll almost never touch this file. Notice the <ion-app></ion-app>: this is the entry point for our ionic app. It’s called the root component of our app.

We’ll see where it’s defined shortly, but this is how Angular 2 apps are built. There is always a <root-component></root-component> kind of structure in the index.html page. The other parts of this file are just loading dependencies, both from vendors/npm, and those built by ionic during development.

I’ll briefly describe the other folders.

app - This is where we’ll spend the most of our time building our app. It contains the structured source code of our app.

node_modules - Contains the npm packages listed in the package.json file. These are packages necessary for building the ionic app.

platforms - This is where platform specific builds, build tools and packages/libraries are stored. You will find a folder for the platform your are building on. To add a platform, android for example, simply run ionic platform add android, and this will add the folder android folder to this folder.

plugins - This is where cordova plugins will be stored when they are installed. Cordova plugins enables your app to have native functionality in the mobile device, e.g accessing the media storage of the device, or even the bluetooth API.

resources - This also contains platform specific resources.

typings - This contains files that help TypeScript infer types it is not aware of. Not all JavaScript libraries were written in TypeScript, and for TypeScript to know about them, we’ll need these libraries’ typings.

The rest of the files are used for building the ionic app into the www folder. We don’t need to know how this works for now.

The app.html is the view/template for our app component. It’s simply the root page where all our app pages will be loaded.

The app.ts is the TypeScript file that defines our root App Component. It has a class MyApp defined. We’ll look more into this when buidling the app.

An Ionic 2 app is divided into pages which are contained in the Pages directory. You could think of them as what page is viewable on the screen at a particular given time (An Activity for Android Developers). The concept is actually interesting, because pages in ionic 2 are put in a stack, one on top of each other, and navigation back is as simple as removing the top most page in the stack (Last In First Out).

The Themes folder contains sass files that help in theming the application.

The Structure of our Sample Ionic App

We’ll make use of the live reloading provided by the Ionic CLI.

$ ionic serve

Our Ionic App will have 3 main pages. One for github users, another for github organisations and another for github repositories. The last two pages are just views to show that we can navigate with the side bar, they will not have any content. The github users page, however, will enable you to view the details of the user.

Delete everything in the app/pages folder, and clear the content of app/theme/app.core.scss file. Then we’ll first quickly create the three main pages with help from the Ionic CLI. Run these in your terminal

This will create three folder with the respective names. g is an alias for generate, so you can still do ionic generate page pageName. Go into each of the folders and replace the content of the html files to look like this.

The <ion-navbar> is responsible for the navigation bar. We could say it’s the navigation component in this case.

menuToggle is a built in directive to help toggle the side menu.

We then have <ion-icon>, which is a component responsible for handling icons. We simply give it the icon name based on this ionic icons list.

The <ion-title> displays the page title.

The <ion-content> holds the contents of the page. It has a padding directive that provides a little padding to the contents.

We’ll then add these pages to our side nav. Go to app/app.ts and we’ll make a few chages. If you check closely there is a class property called pages. This is what composes the sidenav view, as show in the app/app.html

We will not touch this file too, we will just use it as it was generated. The button has an *ngFor="let p of pages" directive, this is how Angular 2 performs repeating in templates. It simply means loop through the pages collection and generate a template for each item in the collection. So if we change the value of the pages property, we change the content of the sidenav.

The <ion-nav> is where the page navigated to is displayed. The root property is bound to rootPage in the page class. We’ll see definition this in detail shortly.

To add the correct pages in the sidenav, we’ll make a few changes to the app/app.ts file. I have commented out two import statements at the for the pages we deleted, and added import statements for the pages we created. You can delete them if you want instead of commenting them out.

The UsersPage, ReposPage and OrganizationsPage are component classes that represent the pages that were scaffolded when we generated the individual pages. You can check them out in app/pages/users/users.ts, app/pages/repos/repos.ts and app/pages/organizations/organizations.ts.

Notice that the rootPage class property is set to the UsersPage. Remember that in the view app/app.html the <ion-nav> root property was bound to this rootPage. This means that the UsersPage will be shown first when the app loads.

We have changed the value of this.pages in the constructor to match the pages that we added.

Running serve in the terminal then going to http://localhost:8100 should output the app.

Getting Github Users

We’ll create a service for getting Github users from https://api.github.com/users. The page lists about 30 of the first github users in json format.

First, we need to create a Github user model. This is a class that holds the relevant fields we want for a github user, since github offers a lot of details.

Create a folder called models in the app folder. This is where we will put our User model and other models we may wish to create later on. Inside app/models and add a file user.ts.

We will not use all the properties of this model. Now that we have our model defined, we can create a github-users provider to enable us pull the users from github. To generate a provider run the following in your terminal

$ ionic g provider github-users

This creates a folder called providers in the app folder, and another github-users folder with a github-users.ts file.

The @Injectable() decorator is how Angular 2 declares it’s services/providers.

The first thing we did was to import the user model with import {User} from '../../models/user'.

Then, notice a function load has been scaffolded for you to load the data you want, all you need to do is edit the path to the json data, which in this case is https://api.github.com/users/, and call your provider somewhere as GithubUsers.load().

We changed the line with this.http.get(''path/to/data.json), replace it so that now you have this.http.get('https://api.github.com/users'). We’ve also changed the property data from the scaffolded class to githubUsers.

Finally, we want results from Github to be converted into an array of users. We do this by casting the json result into an array of users with .map(res => <Array<User>>(res.json())), just below the this.http.get('https://api.github.com/users').

Viewing Github Users

Now that we have our users, it’s time to view them in the users page. Before we can do this, we need to test whether we get users from our provider.

We’ve made a few modifications. First, we’ve imported the GithubUsers Provider at the top with import {GithubUsers} from '../../providers/github-users/github-users';.

Then to use a provider in Angular 2, we need to pass it in the providers property of our component decorator, in this case its the @Component. So you’ll notice we’ve providers[GithubUsers] as one of the properties.

In the constructor of our UsersPage, we’ve added githubUsers: GithubUsers as one of the parameters. This is how we inject dependencies in Angular 2. We then call the load function in the constructor and log the result with console.log.

Make sure ionic server is running, if not, run ionic serve in your terminal, then head over to https://localhost:81000, and open the console panel in Chrome Dev Tools .

You should see that an array of objects has been logged to our console, and on further inspection, it has almost all the properties of our user model.

To view the users in our view page, we need a local variable in the UserPage class that will be an array of Users. Update your User page component to look like this.

We’ve made a few updates. First of all, we import the User Model with import {User} from '../../models/user'; at the top.

We then decalre a local variable of type Array of Users immedialtely after defining the class, users: User[];. This is TypeScript’s way of defining the type of the users class property. It means the users property is of type array of User.

Finally, we update the result of the GithubUsers provider. We’ve used the arrow function then(users => this.users = users). This assigns the result of the promise to the local property users.

We now edit the html view to display the github users. We’ll use an ion-list which is a copmonent provided by ionic for rendering lists.

The items in the list have an ion-item directive which we will loop through with Angular 2’s built in *ngFor directive. We loop through all of the users with *ngFor="let user of users".

We then user property binding to load the avatar within ion-avatar, which just adds a rounded border to the image. Remember our user model had an avatar_url property, hence the user.avatar_url.

We then add the user’s github username, which in this case is {{user.login}}.

The ion-icon is used for loading ionic icons. You could easily use <ion-icon name="arrow-forward"></ion-icon> but we used ios="ios-arrow-forward" md="md-arrow-forward" as a way to show how to load platform specific icons, in this case, ios and android.

The item-right directive puts the icon to the far right of the list item.

Spin up the server if it’s not running with ionic serve in your terminal, the head over to http://localhost:8100. You should see this.

Viewing User Details

Next, we’ll create the details view for users which will be reached by clicking on a particular user in the list of users.

Using the Ionic CLI, create a new page called user-details

$ ionic g page user-details

A user-details folder is created inside pages folder, and has three files, the page’s html, the ts and the scss for styling. Before we do anything we need to make sure that by clicking a user, this page is loaded. First of all let’s make a few changes.

First of all we import the UserDetailsPage at the top with import {UserDetailsPage} from '../user-details/user-details'.

We then add a method that will handle the navigation, goToDetails. It takes in two arguments, the event, just in case we want to do something with the event that triggered the navigation, and the login(username).

Ionic 2 treats navigation as a stack, meaning pages are added on top of each other. That is why you see the this.nav.push, and we push a page into the navigation stack. Going back or pressing the back button is like popping the last element in the stack (Last In First Out). The second parameter of the push is the object we wish to pass to the next page.

We’ve simply added NavParams to the existing imports to enable us access the navigation parameters.

Then, declared a login property of type string.

We inject the NavParams provider in the constructor as navParams, which we then use to get the value of the passed parameter from the previous page with this.login = navParams.get('login') . This should update the user’s login/username correctly in our details view.

If you go to http://localhost:8100, you should be able to click on a user and see this.

The username/login of the user you clicked should be the as a title in the view.

Get correct user details.

Now that we have the user in our details vew, we need to get his specific details. To do this we need to edit the GithubUsers provider to handle the request. The request will be made to https://api.github.com/users/{login}, where we pass in the username/login as the last parameter.

We’ve added an almost identical method to the initail load() called loadDetails(). It takes in a string as a parameter and returns a promise of type User, hence the return new Promise<User>() syntax.

The http.get request is sent to https://api.github.com/users/${login}. This is ES6 template strings, also available in typescript. It Involves using backticks, the key below the escape key on the keyboard, and passing any values with the ${var} syntax, and it will reolve to a valid string.

We then cast the response to a User object and resolve the promise in the observable subscribe method.

We’ve first of all imported the GithubUsers provider with import {GithubUsers} from '../../providers/github-users/github-users';.

We then import the user model with import {User} from '../../models/user';.

To use the provider, we have to add it to the providers property of the @Component decorator, providers: [GithubUsers]. We then inject it in the constructor as githubUsers then call the githubUsers.loadDetails with the value retrieved from the navigation params login. We’ve decided to log the results.

Go to http://localhost:8100, and click on a user, you should see this.

If you expand the logged object, you’ll see it has the properties of our user model.

GithubUsers provider

Notice that we used the GithubUsers twice in our app. Angular 2 is designed to have singleton existence of providers. We can refactor this by declaring GithubUsers provider in our root component/page which is app/app.ts as a provider, and then deleting the providers: [GithubUsers] property in all other components.

Display User details

Now that we have the details of the user, we should display them in the view. We’ll only display the followers, following, public repos and public gist numbers.

Let’s remove the console.log from the user-detail.ts file, and change it to this.

We’ve added a search bar with <ion-searchbar>, and should have a searchbar at the top of the page.

The logic behind searching is simple. Since we have a list already, we’ll just update the list with our result. The github api enables you to search through the following url structure https://api.github.com/search/users?q={searchParam}, with a searchParam.

We’ll first of all create a provider method for search in our GithubUsers Provider. The method is also almost similar to the loadDetails method

app/providers/github-users/github-users.ts

// Imports commented out for brevity
@Injectable()
export class GithubUsers {
// Code commented out for brevity
load() {
// Method implementation commented out for brevity
}
// Get user details from the github api
loadDetails(login: string) {
// Method implementation commented out for brevity
}
// Search for github users
searchUsers(searchParam: string) {
// get the data from the api and return it as a promise
return new Promise<Array<User>>(resolve => {
// Change the url to match https://api.github.com/search/users?q={searchParam}
this.http.get(`https://api.github.com/search/users?q=${searchParam}`)
// Cast the result into an array of users.
// The returned json result has an items
// property which contains the users
.map(res => <Array<User>>(res.json().items))
.subscribe(users => {
resolve(users);
});
});
}
}

The searchUsers method takes in a search parameter, which it will pass to the api url. We then return a promise of type Array<Users> like we did initially for the load method.

Two major changes here. We’ve added a private key word to the githubUsers in the cnstructor where it is injected as a parameter. This makes the property to be available within the class and be accessible with the this keyword. It’s a nifty feature of TypeScript. You can read more about this in using typecript classes.

Our search function is structured to only work when the search parameters are more than three. Go to http://localhost:8100, and try searching for a term, or a username you know.

Clicking any of the result should take you to that user’s profile.

Build/Run the application.

Android

You need to have the android sdk set up. The installation instructions for your specific platform can be found here.

Add android platform to your application

$ ionic platform add android

This adds a folder android within the platforms folder in your app and adds the neccesarry resources needed to build an android application.

Build the android app

$ ionic build android

This builds the application, and puts the built apk in the platforms/android/build/outputs folder.

Run the android app

$ ionic run android

This will run the app in either your default emulator, or a phone connected to your computer with usb debugging enabled.

IOS

To build for ios, you need to be using MacOs and have xCode installed. You also need two node modules installed globally. They just help in building and deploying the app.

$ npm install -g ios-deploy
$ npm install -g ios-sim version

Add ios platform to your project.

$ ionic platform add ios

This adds a folder ios within the platforms folder in your app and adds the necesarry resources needed to build an ios application.

Build your app for ios

$ ionic build ios

This builds the application, and puts the build output in the platforms/ios/build/emulator folder.

Then run the application in an ios simulator that comes installed with xCode

$ ionic run ios

Conclusion

Building Ionic 2 Apps is pretty intuitive and cleaner once you have an understanding of how Angular 2 works. Ionic handles its views as components. You can build an application really quickly, especially if you have your api already defined somewhere.

I think Ionic plays a major role, especially in the development of Progressive Web Apps. If anyone is looking to invest some time in them, they should definitely give Ionic a shot.